The Sensation of Pressure

We feel pressure on our skin, when we place our hand over the outlet of a bicycle pump, for example, as a kind of springy push. Actually, pressure is the summed bombardments of thousands of molecules of air, whizzing about in random directions (as opposed to a wind, where the molecules predominantly flow in one particular direction). If you hold your palm up to a high wind you feel the equivalent of pressure - bombardment of molecules. The molecules in a confined space, say, the interior of a...

 Opinion is Not Necessarily a Good Thing

We live in a civilization that believes that opinion per se is good. This can be seen in the very derivation of the word, which comes from the Latin opinari, meaning to think. It is a fundamental tenet of our civilization that thinking is good, a noble process which is one of the few things separating us from the base animal world. I too believe that thinking is a noble calling and that it is necessary to have opinions for the sake of the kind of thinking that can lead us to a better world. ...

 An Example of the Joy of Hard Science Fiction

If they are going to sink below, then the pressure on the vessel is going to rise as Verne talked about in 20,000 Leagues Under the Sea. If the pressure on the vessel is going to rise, then it's going to collapse unless the pressure within the vessel rises. So the captain is slowly letting the vessel sink into the Moon dust, while the crew is not letting onto the tourists that anything is wrong, but the pressure is slowly going up. Now just as we don't typically notice the pressure go up or ...

 Thoughts on a Collapsing Wall

One summer day, while I was walking along the country road on the farm where I was born, a section of the stone wall opposite me, and not more than three or four yards distant, suddenly fell down. Amid the general stillness and immobility about me the effect was quite startling. ... It was the sudden summing up of half a century or more of atomic changes in the material of the wall. A grain or two of sand yielded to the pressure of long years, and gravity did the rest.

 The Advancement of Science Out of the Amateur

To-day, science has withdrawn into realms that are hardly understanded of the people. Biology means very largely histology, the study of the cell by difficult and elaborate microscopical processes. Chemistry has passed from the mixing of simple substances with ascertained reactions, to an experimentation of these processes under varying conditions of temperature, pressure, and electrification—all requiring complicated apparatus and the most delicate measurement and manipulation. Similarly, ...

 How a Swim Bladder Works

The swim bladder is perhaps the major key to the teleosts' success, and it is well worth a digression to explain it. It is an internal bladder filled with gas, which can be sensitively adjusted to keep the fish in hydrostatic equilibrium at any desired depth. If you ever played with a Cartesian Diver as a child you'll recognize the principle, but a teleost fish uses an interesting variant of it. A Cartesian Diver is a little toy whose business part is a tiny upended cup, containing a bubble o...

 America Forced Christianity to Become More Tolerant

Under the pressure of the American environment, Christianity grew more humanistic and temperate - more tolerant with the struggle of the sects, more liberal with the growth of optimism and rationalism, more experimental with the rise of science, more individualistic with the advent of democracy. Equally important, increasing numbers of colonists, as a legion of preachers loudly lamented, were turning secular in curiosity and skeptical in attitude.